Boric acid esters



United States Patent 3,445,498 BORIC ACID ESTERS Henryk A. Cyba,Evanston, Ill., assignor to Universal Oil Products Company, Des Plaines,11]., a corporation of Delaware No Drawing. Filed May 25, 1965, Ser. No.458,786 Int. Cl. C07f /04; C10m 1/54 U.S. Cl. 260-462 4 Claims ABSTRACTOF THE DISCLOSURE Reaction product of a polyhydroxyaromatic compound, aborylating agent, and an N,N-di-hydrocarbyl hydroxyamine formed at atemperature of from about 60 to about 200 C. The compounds are useful asstabilizing additives for plastics, rubbers, hydrocarbon distillates andother organic substrates normally subject to oxidative deterioration.

This invention relates to a novel reaction product and to the usethereof as an additive in organic substrates.

The novel composition of matter of the present invention is the productformed by reacting a polyhydroxyaromatic compound, a borylating agentand an N,N-disubstituted hydroxyamine. As will be hereinafter set forth,the exact structure of the reaction product will vary primarilydepending upon the particular configuration of the polyhydroxyaromaticcompound and also on the particular borylating agent and the particularhydroxyamine used as reactants. Accordingly, the reaction product isbeing claimed in this manner in the present application.

In one embodiment the polyhydroxyaromatic compound contains the hydroxylgroups in proximity to each other as, for example, in catechol, and insuch cases the reaction with the borylating agent will result in theformation of a cyclic borate. In the formation of the cyclic borate twovalences of the boron are satisfied and this leaves one unsatisfiedvalence which will react with the hydroxyamine. On the other hand, whenthe hydroxy groups of the polyhydroxyaromatic compound are positionedfurther apart as, for example, in hydroquinone, one mole proportion ofthe borylating agent will react with each hydroxy group. The productundoubtedly will include a mixture of different compounds includingmonosubstituted hydroquinone, di-substituted hydroquinone and perhaps apolymer formed by the reaction of one molecule of boric acid with thehydroxyl groups of different hydroquinone molecules. When three hydroxygroups are positioned on adjacent carbon atoms as, for example, inpyrogallol, all of the above reactions may occur, depending upon theratio of the reactants, temperature, solvent used in the reaction andthe mode of addition of the reactants.

Any suitable polyhydroxyaromatic compound is used as a reactant inpreparing the novel composition of matter of the present invention. Inone embodiment the polyhydroxyaromatic compound is catechol andsubstituted catechols. The substituted catechols may contain one or morenuclear substituents which preferably are selected from alkyl of from 1to carbon atoms and which may be primary, secondary or tertiaryconfiguration, cycloalkyl of from 3 to 10 carbon atoms, alkoxy of from 1to 12 carbon atoms or halogen. A particularly preferred substitutedcatechol is tertiarybutyl catechol. Other polyhydroxyaromatic compoundscontaining the hydroxyl groups in adjacent positions include1,2-dihydroxynaphthalene, 1,2-dihydroxyanthracene,1,2-dihydroxyanthroquinone, 1,2-dihydroxydiphenyl, saligenin, etc., aswell as these compounds containing one or more nuclear substitutions,the substitutions preferably being selected from those hereinbefore setforth. Other dihydroxyaromatic compounds containing the hydroxyl groupsin adjacent positions include 2,3-dihydroxybenzophenone,2,3-dihydroxyacetophenone, 2,3-dihydroxypropiophenone,2,3-dihydroxybutyrophenone, 2,3-dihydroxyvalerophenone, 2,3-dihydroxycaprylophenone, 2,3 dihydroxylaurylphenone,2,3-dihydroxypalmitylphenone, etc., as well as the corresponding 3,4-,4,5- or 5,6-dihydroxy compounds, 1',2',3,4-,5,6-hexahydro-2,3-dihydroxybenzophenone, and these compoundscontaining one or more substitutions preferably selected from thosehereinbefore set forth. Also included in dihydroxy-substituted compoundsin which the hydroxyl groups are in sufficiently close proximity toresult in chelate formation are 2,2'-dihydroxybenz0phenone and thenuclear substituted derivative thereof.

Still other suitable polyhydroxy compounds are polyhydroxydiphenylalkanes, ethers, sulfides and amines. Of the polyhydroxydiphenylalkanes, the methanes, ethanes, propanes and butanes are preferred,although the alkane group may contain up to 12 or more carbon atoms. I1-lustrative reactants in this example include 2,2-dihydroxydiphenylmethane, 2,3,2,3-tetrahydroxydiphenyl methane, 3,3-dihydroxydiphenylmethane, 4,4'-di.hydroxydiphenyl methane, 3,4,3,4-tetrahydroxydiphenylmethane, and these compounds containing substituents, the substituentspreferably being selected from those hereinbefore set forth, similarpolyhydroxydiphenyl ethanes, polyhydroxydiphenyl propanes,polyhydroxydiphenyl butanes, polyhydroxydiphenyl pentanes,polyhydroxydiphenyl hexanes, etc. Illustrative polyhydroxydiphenylethers include 2,2-dihydroxydiphenyl ether,2,3,2,3'-tetrahydroxydiphenyl ether, 4,4'-dihydroxydiphenyl ether, etc.,and substituted derivatives thereof. Illustrative polyhydroxydiphenylsulfides include 2,2'-dihydroxydiphenyl sulfide,2,3,2',3'-tetrahydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfide,etc., and substituted derivatives thereof. Illustrativepolyhydroxydiphenyl amines include 2,2'-dihydroxydiphenyl amine,2,3,2,3'-tetrahydroxydiphenyl amine, 4,4-dihydroxydiphenyl amine, etc.,and substituted derivatives thereof.

Still another type of polyhydroxy compound includes thepolyhydroxyspirochromans. Illustrative polyhydroxyspirochromans include6,7-dihydroXy-bis-2,2-spirochroman and6,7,6,7'-tetrahydroxy-bis-2,'2-spirochroman, and their substitutedderivatives, the substitutions preferably being selected from thosehereinbefore set forth. Specific examples of such substitutedpolyhydroxyspirochromans include 6,6,7,7' tetrahydroxy 4,4,4',4'tetramethyl-bis- 2,2'-spirochroman,6,6',7,7'-tetrahydroxy-4,4-diethyl-bis- 2,2-spirochroman,6,6',7,7'-tetrahydroxy 4,4 dimethyl-4,4'-di-n-hexyl-3-n-amyl-bis-2,2'-spirochroman etc.

As hereinbefore set forth, pyrogallol and substituted pyrogallolscontain the hydroxyl groups in adjacent positions so that two of thehydroxyl groups may react with the borylating agent to form a cyclicstructure. Other polyhydroxyaromatic compounds containing three hydroxylgroups include hydroxyhydroquinone, phloroglucinol, etc. In anotherembodiment, the hydroxyl groups are not on adjacent carbon atoms as, forexample, in resorcinol, hydroquinone, 1,3,5-trihydr0xybenzene, etc., andtheir substituted derivatives.

From the above discussion it will be seen that any suitablepolyhydroxyaromatic compound may be used as a reactant in preparing thenovel composition of the present invention. When the hydroxyl groups arepositioned on adjacent carbon atoms or are in close proximity, a cyclicconfiguration occurs. When the hydroxyl groups are positioned furtherapart from each other, a cyclic structure is not obtained. It isunderstood that the different polyhydroxyaromatic compounds will notnecessarily react identically but all of them will react to form desiredcompositions of matter.

The novel reaction product includes the reaction with a borylatingagent. Any suitable borylating agent may be used. A particularlypreferred borylating agent is boric acid. Other borylating agentsinclude trialkyl borates in which the alkyl groups preferably containfrom 1 to 4 carbon atoms each. In the use of the latter type borylatingagent, the reaction is effected by transesterification and, accordingly,there is no advantage to using trialkyl -borates containing more than 4carbon atoms in each alkyl group, although the higher boiling trialkylborates may be used when satisfactory and advantages appear therefor.Still other borylating agents include boric anhydride, boric oxide,boric acid complex, alkyl boric acid, dialkyl boric acid, cycloalkylboric acid, dicycloalkyl boric acid, aryl boric acid, diaryl boric acid,alkylboronic acid, arylboronic acid, or substitution products of thesewith allcoxy, alkyl and/ or halo groups.

The other reactant for use in preparing the novel reaction product ofthe present invention is an N,N-di-substi tuted hydroxyamine. In oneembodiment this is an N,N- di-substituted alkanolamine. .In a preferredembodiment the alkanol moiety contains from 2 to 6 carbon atoms,although it may contain up to 12 or more carbon atoms when desired. Thesubstitutions on the nitrogen atom preferably are hydrocarbyl and thusare selected from :alkyl, cycloalkyl and aryl. The alkyl substituentsmay contain from 1 to about 20 and preferably from 3 to 15 carbon atomseach, Illustrative N,N-dialkyl-ethanolamines includeN,N-diisopropylethanolamine, N,N-disec'butyl ethanolamine,N,N-di-secpenty'l-ethanolamine, N,N-di-sechexyl-ethanolamine,N,N-di-secheptyl-ethan'olamine, N,N-di-secoctyl-ethanola-mine, N,N disecnonylethanolamine, N,N di secdecyl ethan-olamine,N,N-disecundecyl-ethanolamine, N,N di secdodecyl ethanolamine,N,N-di-sectridecyl-ethanolamine, N,N-di-sectetradecylethanolamine,N,N-di-secpen-tadecyl ethanolamine, etc. A preferredN,N-dicycloalkyl-ethanolamine is N,N- dicyclohexyl-ethanolamine. OtherN,N-dicycloalkyl-ethanolamines include N,N-dicyclobutyl-etlhanolamine,N,N- dicyclopentyl-ethanolamine, N,N-dicycloheptyl-ethanolamine,N,N-dicyclooctyl-ethanolamine, N,N-dicyclononylethanolamine,N,N-dicyclodecyl-ethanolamine, etc. IllustrativeN,N-diaryl-ethanolamines include N,N-diphenylethanolamine, N,N ditolylethanolamine, N,N-dixylylethanolamine, etc. The above examples are ofdi-substituted ethanolamines, it being understood that the correspondingpropanolamines, butanolamines, pentanolamines, hexanolamines, etc., mayhe used when desired.

In another embodiment the N,N-di-substitu-ted hydroxyamine is ahydroxyaromatic amine. Illustrative compounds in this embodiment includeN,N-dialkyl-hydroxyaniline, N,N-dicycloalkyl-hydroxyaniline,N,N-diphenylhydroxyaniline and the nuclear substituted derivativesthereof. It is understood that the substitutions on the nitrogen atomwill be selected from those hereinbefore set forth. In a preferredembodiment the nitrogen atom and hydroxyl group are in paraposition toeach other but these may be in the orthoor meta-positions to each other.In another embodiment the N,N-di-substit-uted hydroxyamine is anN,N-di-substituted hydroxycyclohexyl amine in which the hydroxy andamino groups are in position ortho-, metaor parato each other and inwhich the substitutions on the nitrogen atom are selected from thosehereinbefore set forth.

The reaction of the polyhydroxyaromatic compound, borylating agent andN,N-di-substituted hydroxyamine is effected in any suitable manner. Inone method the reactants in the desired proportions are mixed and themixture is heated and refluxed to effect the desired reaction. Inanother method the polyhydroxyaromatic compound and borylating agent arefirst reacted and then the N,N- di-substituted hydroxyamine is reactedwith the .partial reaction products. In still another embodiment theborylating agent and N,N-di-substituted hydroxyamine are first reactedand then the partially reacted products are .4 further reacted with thepolyhydroxyaromatic compound.

Regardless of the particular method of reacting, the reaction iseffected by heating and refluxing the mixture of reactants. In oneembodiment the reaction is effected at a temperature within the range offrom about 60 to about C. when using boric acid. When chelate formationdoes not occur, the reaction may be effected at a temperature aboveabout 100 C. and thus within the range of from about 100 to about 200 C.or more, in which reaction meta-borates are formed. Also, the highertemperature of from about 100 to about 200 C. is used when employingtrialkyl borates in order to effect the transesterification reaction.

In one method the reactants are refluxed in the presence of a solvent.Any suitable solvent may be used and advantageously comprises anaromatic hydrocarbon solvent including benzene, toluene, xylene,ethylbenzene, cumene, etc. Other solvents include n-hexane, n-heptane,n-octane, chlorinated hydrocarbons, etc., or mixtures thereof. The useof a solvent is particularly preferred when boric acid is used as theborylating agent. When using a trialkyl borate as the borylating agent,the solvent may be omitted. While no catalyst normally is required, acatalyst may be used when employing the trialkyl borate. Any suitablecatalyst may be employed including sodium hydrogen sulfate, potassiumhydrogen sulfate, tin oxide, polyalkyl tin derivatives, alkoxy titaniumderivatives, trialkyl or trialkoxy aluminum, toluene sulfonic acid,benzene sulfonic acid, various sulfonated ion exchange resins, solidphosphoric acid, polyphosphroic acid, sulfuric acid and in fact anysuitable esterification or transesterification catalyst.

The temperature of the refluxing will depend upon the particular solventemployed. For example, with benzene as the solvent, the temperature willbe of the order of 80 C. When using toluene, the temperature will be ofthe order of C. When using xylene, the temperature will be of the orderof C.

The proportions of borylating agent, polyhydroxyaromatic compound andN,N-di-substituted hydroxyamine will vary depending upon the particularreactants employed. In general the proportion of borylating agent topolyhydroxyarornatic compound will be within a mole raito of 0.5 to 4and preferably from about 1 to about 3 mole proportions of borylatingagent per one mole proportion of polyhydroxyaromatic compound. TheN,N-disubstitutcd hydroxyamine generally will be used in equal moleproportions to the borylating agent but may vary from 0.5 to 3 moleproportions of the hydroxyamine per one mole proportion of borylatingagent.

As hereinbefore set forth the reaction is readily effected by heatingand refluxing the reactants, with or without solvent and/or catalyst asrequired. Refluxing is continued until the required amount of water whenusing boric acid or of alcohol when using trialkyl borate is collected.Following completion of the reaction the solvent and alcohol, if any,are removed by vacuum distillation. The reaction product generally isrecovered as a solid and may be used as such or when desired thereaction product may be retained in the solvent and used as such or thereaction product may be prepared as a solution in a different solventand used in this manner.

From the above discussion it will be seen that the exact structure ofthe reaction product may vary and also that the reaction product mayconsist of a mixture of compounds. It is understood that the differentreaction products meeting the requirements as hereinbefore set forth maybe used for the purposes of the present invention but that the differentadditives are not necessarily equivalent in their effectiveness in thesame or different substrates.

The novel compounds of the present invention possess varied utility.They are particularly advantageous for use as additives in organicsubstances subject to oxidative deterioration. These compounds alsoserve as weathering stabilizers to protect substrates which undergoultraviolet light-induced oxidation. Also, they may serve as antimildew, fungicide, bactericide, etc., additives for organic substrates,especially fibers, cloth, paint, varnish, other coatings, fuels, etc.,or as antistatic or antiblocking additives and as dye sites in plastics.The substrates normally subject to exposure to weather include plastics,resins, paints, varnishes, other coatings, fibers, textiles, etc.

Illustrative plastics which are stabilized by the novel compounds of thepresent invention include polyolefins and particularly polyethylene,polypropylene, polybutylene, mixed ethylene propylene polymers, mixedethylene butylene polymers, mixed propylene butylene polymers, includingthe above copolymerized with straight chain or cyclic diene to giveterpolymers which can be cured to rubbers, etc. The solid olefinpolymers are used in many applications including electrical insulation,lightweight outdoor furniture, awnings, cover for greenhouses, fibers,etc. In many of these applications the solid olefin polymer is exposedto sunlight and air.

Another plastic being used commercially on a large scale is polystyrene.The polystyrene type resins are particularly useful in the manufactureof molded or machined articles which find application in such goods aswindows, optical goods, automobile panels, molded household articles,etc. One disadvantage of polystyrene is its tendency to deteriorate whenexposed to direct sunlight and air for extended periods of time.

Another class of plastics available commercially is broadly classed asvinyl resins and is derived from monomers such as vinyl chloride, vinylacetate, vinylidine chloride, etc. Polyvinyl chloride plastics areavailable commercially on a large scale and undergo deterioration whenexposed to sunlight. Other vinyl type resins include copolymers of vinylchloride with acrylonitrile, methacrylonitrile, vinylidine chloride,alkyl acrylates, alkyl methacrylates, alkyl maleates, alkyl fumarates,polyvinyl butyral, etc., or mixtures thereof.

Other plastics being used commercially on a large scale are in thetextile class and include nylon (polyamide), Perlon L or 6-nylon(polyamide), Dacron (terephthalic acid and ethylene glycol), Orlon(polyacrylonitrile), Dynel (copolymer of acrylonitrile and vinylchloride), Acrilan (polyacrylonitrile modified with vinyl acetate),saran (copolymer of vinylidine chloride and vinyl chloride), rayon, etc.Here again, deterioration occurs due to ultraviolet light and oxidation.In addition, the additives of the present invention may serve as dyesites in plastics. This is especially desirable in plastics used fortextiles as, for example, use of plastics for carpeting, fabrics, etc.Furthermore, the additives of the present invention also may inhibitdiscoloration of the plastic.

Still other plastics are prepared from other monomers and are availablecommercially. Illustrative examples include polyurethanes, both theurethane foams and the rigid resins, epoxy resins, polycarbonates, etc.Still other illustrative examples include phenol-formaldehyde resins,urea-formaldehyde resins, melamine-formaldehyde resins, acryloidplastics which are derived from methyl, ethyl and higher alkyl acrylatesand methacrylates as monomers used in the polymerization. Other polymersinclude polyacetals, especially polyformaldehydes such as Delrim" andCelcon. Still other substrates include vinyl, acrylic, nitrocellulosebased coatings; especially cellulose acetate, cellulose acetatebutyrate, ethyl cellulose, etc. Still other substrates are polyesters,including linear or cross-linked, reinforced polyesters, laminatepolyesters, etc., various latexes, lacquers, alkyds, varnishes,polishes, stains, pigments, dyes, textile finishing formulations, etc.

It is understood that the plastic may be fabricated into any desiredfinished product including moldings, castings, fibers, films, sheets,rods, tubing or other shapes.

Rubber is composed of polymers of conjugated 1,3- dienes, either aspolymers thereof or as copolymers thereof with other polymerizablecompounds, and the rubbers, both natural and synthetic, are included assolid polymers in the present specifications and claims. Syntheticrubbers include SBR rubber (copolymer of butadiene and styrene), Buna N(copolymer of butadiene and acrylonitrile), butyl rubber (copolymer ofbutadiene and isobutylene), neoprene rubber (chloroprene polymer),Thiokol rubber (polysulfide), silicone rubber, etc. The natural rubbersinclude hevea rubber, cautchouc, balata, gutta percha, etc. It is wellknown that rubber undergoes deterioration due to oxygen and, whenexposed to direct sunlight for extended periods of time, also undergoesdeterioration from this source.

The above are illustrative examples of various plastics and resins whichare improved by the additives of the present invention. As hereinbeforeset forth, still other substrates include paints, varnishes, dryingoils, pigments, rust preventive coatings, wax coatings, protectivecoatings, etc. It is understood that the compounds of the presentinvention may be used in any coating which is subject to exposure toultraviolet light, oxidation, heat, etc. While the compounds areespecially useful in materials subject to such exposure, it isunderstood that the compounds of the present invention also may be usedadvantageously in other coatings, plastics, resins, paints, etc., whichnormally are not exposed outdoors.

The compounds of the present invention also are of utility as additivesin other organic substrates including, for example, hydrocarbondistillates. Illustrative hydrocarbon distillates include gasoline,naphtha, kerosene, jet fuel, solvents, fuel oil, burner oil, range oil,diesel oil, marine oil, turbine oil, cutting oil, rolling oil, solubleoil, drawing oil, slushing oil, lubricating oil, fingerprint remover,wax, fat, grease, etc. In the oils, the compounds of the presentinvention serve to inhibit oxidative deterioration, thermaldeterioration, etc., thereby retarding and/ or preventing sedimentformation, preventing and/or retarding discoloration, rust or corrosioninhibitor, detergent, dispersing agent, etc. In gasoline, the additiveimproves the combustion characteristics of the gasoline.

In many applications it is advantageous to utilize the compounds of thepresent invention in conjunction with other additives. For example,particularly improved results are obtained in the stabilization ofplastics, apparently due to a synergistic effect, when the compound ofthe present invention is used in admixture with a phenolic antioxidantincluding particularly 2,6-ditertiarybutyl-4- methylphenol. Otherinhibitors which ;may be used generally will be of the phenolic or aminetype and include phenyl-alpha-naphthyla'mine, phenyl-beta-naphthylamine,phenothiazine, Nonox WSP, Nonox Cl, dialkylated phenols, trialkylatedphenols including 2,4--di-methyl-6- tertiarybutylphenol, etc., SantonoxR, Santowhite, alkylalkoxyphenols, 2246 (2,2' methylene-bis (4-methyl-6-tert-butylphenol) and 425 (2,2-methylene-bis-(4-ethyl-6-tert-butylphenol), diphenyl-p-phenylene diamine, 1,1,3- tris (Z-methyl4-hydroxy-S-t-butylphenyl)-butane, 703 (2,6-di-tert butyl-alphadimethylamino-p-cresol), 4,4- bis-(Z-methyl 6-tert-butylphenol);4,4'-thio-bis-(6-tertbutyl-o-cresol); 4,4'-bis(2,6-di-tert-butylphenol); 4,4- methylene-bis (2,6-di-tert-butylphenol);Salol (salicylic acid esters), p-octyl-phenylsalicylate, variousphosgene alkylated phenol reaction products, etc. Other ultravioletlight stabilizers include nickel-bis-dithiocarbamates and especiallynickel-bis-dibutyldithiocarbamate, nickel-bis-dihydroxypolyalkylphenolsulfides, especially [2,2'-thiobis- (4-t-octylphenolato)]-n-butylaminenickel (II), dilauryl beta-mercaptodipropionate, dihydroxy-tetralkylsulfides, dihydroxytetralkyl methanes, various trithiophosphites astrilaurylthiophosphite, dialkylphosphites, trialkylphosppites, highmolecular weight nitriles, various Mannich bases, variousN-hydroxyphenylbenzotriazoles such as 2- (2-hydroxy-5-octylphenyl-benzotriazole, 2-( 2'-hydroxy- 5-dodecylphenyl)-benzotriazole,2-(2'-hydroxy-5'-octoxyphenyl)-benzotriazole, 2-(2-hydroxy-5'dodecoxyphenyl)-benzotriazole, Tinuvin 326, etc., in general, any alkylor alkoxyphenyl substituted benzotriazole, etc. The additional inhibitormay be used in a concentration of from about 1% to about 200% by weightand generally from about 10% to about 75% by weight of the compound ofthe present invention. Generally, the additional inhibitor will be usedin a concentration within the range of from about 0.001% to about 3% andmore particularly from about 0.01% to about 2% by weight of thesubstrate.

The additive of the present invention will be used in a stabilizingconcentration which will depend upon the particular substrate. Theadditive may be used in a concentration as low as 0.0001 76 to about 25%but generally will be used in a concentration of from about 0.01% toabout 5% by weight of the substarte. When used in hydrocarbon distillateand particularly gasoline, the additive generally is used in aconcentration of from about 0.0001 to about 0.5%. The additive isincorporated in the substrate in any suitable manner. For example, whenit is incorporated into a plastic, resin or the like, it may be added tothe hot melt with stirring, generally in a Banbury mixer, extruder orother device. When it is added to a liquid, it is incorporated into theliquid with intimate stirring. When it is added to a multicomponentmixture as, for example, grease, it may be added to one of thecomponents and, in this manner, incorporated into the final mix or itmay be added directly into the final mix.

The additive of the present invention may be utilized as such orprepared as a solution in a suitable solvent including alcohols andparticularly methanol, ethanol, propanol, butanol, etc., hydrocarbonsand particularly benzene, toluene, xylene, cumene, decalin, etc.

The following examples are introduced to illustrate further the noveltyand utility of the present invention but not with the intention ofunduly limiting the same.

Example I The compound of this example was prepared by the re action ofequal mole proportions of 4-tertiarybutyl catechol, boric acid andN,N-dicyclohexyl-ethanolamine. The reaction was effected by commingling33.2 g. (0.2 mole) of 4-tertiarybuty1 catechol, 4.5 g. (0.2 mole) ofN,N-dicyclohexyl-ethanolamine, 12.36 g. (0.2 mole) of boric acid and 100g. of benzene solvent. The mixture was heated and refluxed at atemperature starting at 76 C. After heating and refluxing for six hours,a total of 9.2 m1. of water was collected. In order to insure completionof the reaction, 50 ml. of toluene were added and the refluxingcontinued at a higher temperature, during which time 50 ml. of thebenzene added originally had been removed overhead. Following completionof the reaction 90 g. of product were collected. In order to remove anyimpurities or unreacted amine, the product precipitated and 70 gramswere collected. Analysis showed a boron content of 2.53 by weight whichcorrespondsto a theoretical boron content of 2.72% by weight for thefollowing reaction product:

While applicant believes the reaction product to be of the structure setforth above, it is understood that applicant does not wish to be limitedto this specific compound. However, the reaction of all of the boron isconfirmed by the fact that the impurities or unreacted amine whichdissolved in the hexane fraction mentioned above was submitted for boronanalysis and was found to contain no boron.

Example II The compound of this example is prepared in substantially thesame manner as described in Example I except that the N,N-di-substitutedhydroxyamine used in this preparation is N,N-di-secbutyl-ethanolamine.Equal mole proportions of 4-tertiarybutyl catechol, boric acid andN,N-di-secbutyl-ethanolamine are heated and refluxed for a period of 8hours in benzene solvent, during which time the water liberated in thereaction is recovered. Following completion of the reaction, thereaction product is separated from the solvent and is recovered.

Example III The reaction product of this example is prepared by heatingand refluxing one mole proportion of hydroquinone, two mole proportionsof boris acid and four mole proportions of N,N-diisopropyl-propanolaminein the presence of toluene solvent. The heating and refluxing iscontinued at a temperature of about C., during which time the waterformed in the reaction is distilled overhead and collected. Uponcompletion of the reaction, the reaction mixture is allowed to cool andthe product is recovered in admixture in the solvent.

Because the hydroxy groups are in a position distant from each other,formation of a cyclic product does not occur. It is believed that thereaction product will include the following configuration:

CH3 !H 3 2 a It will be noted that one valence of each of the boron issatisfied by one hydroxyl group of the hydroquinone and that the othertwo valences of the boron are satisfied by two molecules of thepropanolamine.

Example IV The reaction product of this example is prepared by firstreacting saligenin with boric acid and then reacting withN,N-dicyclohexyl-p-hydroxyaniline. The reaction is effected in thepresence of toluene solvent by first heating and refluxing equal moleproportions of saligenin and boric acid for a period of 4 hours and thenadding an equal mole proportion of N,N-dicyclohexyl-p-hydroxyaniline andcontinuing the heating and refluxing for another 4 hours. Followingcompletion of the reaction, the reaction mixture is allowed to cool andthe product is recovered in admixture with the toluene solvent and usedin this manner as an additive to hydrocarbon distillate.

Example V The reaction product of this example is prepared by refluxing2,4-dihydroxybenzophenone, boric acid and N,N- di-secoctyl-ethanolamine.The reaction is effected by heating and refluxing one mole proportion of2,4-dihydroxybenzophenone, one mole proportion of boric acid and twomole proportions of N,N-di-secoctyl-ethanolamine. The refluxing iseffected in the presence of benzene solvent and is continued for aperiod of 8 hours, during which time the water formed in the reaction isliberated and recovered. Following completion of the reaction, thereaction mixture is distilled under vacuum to remove the benzene solventand to recover the desired product. Because two mole proportions of thehydroxyamine are used, it is believed that one valence of the boron issatisfied by one hydroxyl group of the benzophenone and that the othertwo valences of the boron are satisfied by two molecules of theethanolamine.

9 Example VI The reaction product of this example is prepared by thetransesterification reaction in which tributyl borate is used as theborylating agent. The reaction is effected by heating and refluxingequal mole proportions of pyrogallol, tributyl borate andN,N-diphenyl-ethanolamine in xylene solvent. The refluxing is etfectedat a temperature of about 140 C. and is continued until the requiredamount of butanol is collected, the butanol resulting from thetransesterification reaction. Following completion of the reaction, thereaction mixture is worked up in substantially the same manner ashereinbefore set forth and the product is recovered in solution in thexylene solvent used in the reaction.

Example VII As hereinbefore set forth the compound of the presentinvention is useful as an antioxidant in plastic. The plastic of thisexample is solid polypropylene. The solid polypropylene withoutinhibitor is stated to have properties substantially as follows: i

TABLE 1 Specific gravity 0.9100.920 Refractive index, n 1.510 Heatdistortion temperature, at-

66 p.s.i. load C 116 264 p.s.i. load C 66 Tensile yield strength, p.s.i.(ASTM 13-638- 58T) (0.2" per min.) 4700 Total elongation, percent300-400 Stiffness flexural (ASTM D74750) 10 p.s.i 1.8 Shore hardness(ASTM D676-55T) 74D The additive when employed was incorporated in thesample of the polypropylene by milling. The sample of the polypropylenewas evaluated in a method similar to that described by Hawkins, Hansen,Matreyek and Winslow in Rubber Chemistry and Technology, October-November, 1959, pages 11644170, except that an electrically heatedaluminum block rather than an oven was used to maintain the desiredtemperature. The oxygen absorption of the sample was determinedmanometrically rather than volumetrically. In this method samples of thepolypropylene, weighing about 0.5 gram each, are placed in separate 8mm. glass tubes and the tubes then are inserted into horizontal rows ofopenings located concentrically around the heater. The temperature ismaintained at about 140 C. The glass tubing also is packed with glasswool and molecular sieves to absorb the gases. Each of the glass tubesis connected to an individual manometer containing mercury, and thedifferential pressure is periodically determined. The induction periodis taken as the number of hours required to reach a pressuredifferential of 20 cm. Hg.

When evaluated in the above manner, a control sample of thepolypropylene without additive had an induction period of less than 4%hours. Another sample of the polypropylene containing 1% by weight ofthe reaction product of 4-tertbutyl catechol, boric acid andN,N-dicyclohexyl-ethanolamine, prepared as described in Example I, and0.15% by weight of 2,6-ditertbutyl-4-methylphen-ol was evaluated in thesame manner and the induction period was increased to 1100 hours. It isbelieved that the use of the reaction product in admixture with the 2,6-ditertbutyl-4-methylphenol results in a synergistic eifect and increasesthe induction period even more than obtained when using the reactionproduct alone. The 2,6- ditertbutyl-4-methylphenol, when used alone andevaluated in the above manner, was of substantially noeffect inincreasing the induction period of the polypropylene.

Example VIII The plastic of this example is solid polyethylene of thehigh density type. An inhibited product of this polyethylene is marketedcommercially under the trade name of Fortiflex. Samples of thepolyethylene are pressed into plaques and evaluated in the Fadeometer.The plaques are inserted into plastic holders aflixed onto a rotatingdrum and exposed to carbon arc rays at about 52 C. in the Fadeometer.The samples are examined periodically by infrared analysis to determinethe carbonyl band at 1715 cm. which is reported as the carbonyl number.The higher intensity of the carbonyl band indicates a higher carbonylconcentration (expressed as carbonyl number) and, accordingly, increaseddeterioration.

The additive of this example is the reaction product of hydroquinone,boric acid and N,N-diisopropylprop anolamine, prepared as described inExample III, and is incorporated in a concentration of 1% by weight inotherwise uninhibited samples of the polyethylene prior to pressing intosheets. This serves to stabilize the polyethylene and to considerablyincrease the time before a carbonyl number of 1000 is reached.

Example IX The plastic of this example is polystyrene. During millingthereof 1% by weight of the reaction product of 4-tertbutyl catechol,boric acid and N,N-di-secbutyl-ethanolamine, prepared as described inExample II, is incorporated in the polystyrene. This serves to inhibitdeterioration of the polystyrene upon exposure to weathering.

Example X The reaction product of saligenin, boric acid and N,N-dicyclohexyl-p-hydroxyaniline, prepared as described in Example IVexcept that the toluene solvent is removed from the reaction product byvacuum distillation, is utilized as an inhibitor in polyvinyl chlorideplastic. The additive is incorporated by partly melting the polyvinylchloride plastic and adding the inhibitor into the hot melt in aconcentration of 0.75% by weight. This serves to inhibit deteriorationof the polyvinyl chloride plastic upon exposure to oxygen and light.

Example XI The reaction product of 4-tertbutyl catechol, boric acid andN,N-dicyclohexyl-ethanolamine, prepared as described in Example I, wasincorporated in another sample of the polypropylene described in ExampleVII by milling therein in conventional manner and pressing into sheets.The sheets then were cut into dumb-bell specimens and were exposed toweathering on an outerdoor rack facing south and inclined at a 45 angleat Des Plaines, Ill.

Dumb-bell specimens of the polypropylene without additives and dumb-bellspecimens containing 1% by weight of the reaction product describedabove and 0.15% by weight of 2,6-ditertbutyl-4-methylphenol wereevaluated outdoors in the manner described above. Periodically thephysical properties of the samples were determined in an InstromUniversal tester. In this evaluation the dumb-bell specimen is grippedfirmly at the top and bottom in a machine in which a constant pull of 2"per minute is exerted downwardly. The following table reports theresults of the yield point (also called yield strength), which is themaximum point at which the sample first shows loss of physical strengthand is reported in pounds per square inch of load at that point. All ofthese samples were placed outdoors in the month of March.

From the data in the above table it will be seen that the control sample(without additives) dropped in yield point from 4304 to 2604 within 29days. The sample was brittle and lost its desirable physical properties.In contrast, the sample containing the additive still retained a yieldpoint of over 4800 pounds per square inch after 92 days of outdoorexposure, thus showing the elfectiveness of the additive of the presentinvention to stabilize the polypropylene against weathering.

Example XII This example describes the use of the additive of thepresent invention in grease. In this example the reaction product ofpyrogallol, trimethyl borate and N,N-diphenylethanolamine, prepared asdescribed in Example VI, is incorporated in a concentration of 0.3% byweight in a commercial Mid-Continent lubricating oil having an S.A.E-.viscosity of 20. Approximately 92% of the lubricating oil then is mixedwith approximately 8% by weight of lithium stearate. The mixture isheated to about 230 C., with constant agitation. Subsequently the greaseis cooled, while agitating, to approximately 120 C., and then the greaseis further cooled slowly to room temperature.

The stability of the grease is tested in accordance with ASTM D-942method, in which method a sample of the grease is placed in a bomb andmaintained at a temperature of 121 C. Oxygen is charged to the bomb, andthe time required for a drop of five pounds pressure is taken as theinduction period. A sample of the grease without additive will reach theinduction period within 4 hours. A sample of the grease containing 0.5%by weight of the reaction product of the present invention will notreach the induction period until more than 100 hours when evaluated inthe above manner.

Example XIII This example describes the use of the additive of thepresent invention in synthetic lubricating oil. The syntheticlubricating oil is dioctyl sebacate and is marketed commercially underthe trade name of Plexol. The additive is the reaction product of4-tertbutyl catechol, boric acid and N,N-dicyclohexyl-ethanolamine,prepared as described in Example I, and is incorporated in aconcentration of 1% by weight in the synthetic lubricating oil withintimate mixing. This serves to prevent oxidative deterioration of thelubricating oil.

I claim as my invention:

1. The product formed by heating and refluxing 4- tertbutyl catechol,boric acid and N,N-dicyclohexyl-ethanolamine in the presence of benzenesolvent, cooling the reaction mixture, removing the benzene solvent andrecovering the reaction product as a solid.

2. The product formed by reacting a catechol, boric acid and anN,N-di-hydrocarbylalkanolamine in which the alkanol moiety contains from2 to about 12 carbon atoms and each hydrocarbyl substituent is selectedfrom the group consisting of alkyl having up to about car'- bon atoms,cycloalkyl having from 4 to about 10 carbon atoms, phenyl and loweralkyl-substituted phenyl, at a temperature of from about 60 to about200- C., in the presence of an aromatic hydrocarbon solvent.

3. The product formed by reacting a hydroquinone, boric acid and anN,N-di-hydrocarbyl-alkanolamine in which the alkanol moiety containsfrom 2 to about 12 carbon atoms and each hydrocarbyl substituent isselected from the group consisting of alkyl having up to about 20 carbonatoms, cycloalkyl having from 4 to about 10 carbon atoms, phenyland'loWer-alkyl-substituted phenyl, at a temperature of from about 60 toabout 200 C., in the presence of an aromatic hydrocarbon solvent.

4. The product formed by reacting a resorcinol, boric acid and an N,N-dihydrocarbyl-alkanolamine in which the alkanol moiety contains from 2 toabout 12 carbon atoms and each hyd'rocarbyl substituent is selected fromthe group consisting of alkyl having up to about 20 cartemperature offrom about to about 200 C., in the presence of an aromatic hydrocarbonsolvent.

References Cited UNITED STATES PATENTS 2,587,753 3/1952 OConnor et al.260-462 X 2,795,548 6/1957 Thomas et al. 260462 X 3,257,442 6/1966 Woodset al. 260462 BERNARD HELFIN, Primary Examiner.

L. DE CRESCENTE, Assistant Examiner.

US. Cl. X.R.

